The goal of this research is to understand how movement segments are assembled into complex motor sequences. The general hypothesis to be tested t=is that neurons in the supplementary motor area of motor cortex (SMA) are recruited and act as "temporal binders" during the learning and performance of a new movement sequence so that the transitions between movement segments are performed smoothly and without delay. Monkeys will be trained to generate memorized hand movement sequences in the horizontal plane. Simultaneous extracellular unit recordings will be made in SMA and primary motor cortex (MI) during the task performance using single micro- electrodes, micro-wire arrays, and silicon electrode arrays. According to the hypothesis, temporal binding neurons in SMA will be active during particular segment transitions for previously-learned sequences and will increase gradually as novel sequences containing new transitions are learned. In addition, the cross-correlations between successively activated directionally-selective neurons in MI will become stronger at these transitions. Since many forms of learning require the composition of smaller but familiar elements, this research may reveal fundamental mechanisms of learning, particularly of motor-skill learning. In addition, a number of movement disorders such as Parkinson's disease can be characterized as a breakdown in the generation of smooth movement sequence. Therefore, this research could provide insights into the etiology and treatment of such disorders.